Recently, I purchased from Cub Cadet Specialties a new rubber gear shift knob for my IH Cub Cadet 100 tractor. I am very pleased with the quality and appearance of the new gear shift knob. The old (rubber) gear shift knob was hard as a rock, cracked, and fastened to the gear shift shaft by heavy wire, duct tape, and possibly adhesive to boot. I had always assumed the original gear shift knob was hard plastic and threaded onto the shaft. Those assumptions were incorrect. It is simply a very tight interference fit facilitated by a air vent hole at the top of the (rubber) gear shift knob. Quick easy fix!